> ## Documentation Index
> Fetch the complete documentation index at: https://docs.retellai.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Claude Sonnet 4.5 retirement

> Claude Sonnet 4.5 retires on September 29, 2026. Retell AI automatically migrates existing configurations to Sonnet 4.6; no manual migration is required.

Retell will retire Claude Sonnet 4.5 on **September 29, 2026** and automatically migrate existing configurations to Claude Sonnet 4.6. No manual migration is required.

| Deprecated model    | Replacement         | Migration date     |
| ------------------- | ------------------- | ------------------ |
| `claude-4.5-sonnet` | `claude-4.6-sonnet` | September 29, 2026 |

Sonnet 4.5 is no longer offered in the dashboard model pickers. Existing configurations can continue using it until migration. API requests that explicitly submit `claude-4.5-sonnet` are normalized to `claude-4.6-sonnet`, so resubmitting the model in an update switches that configuration before the migration date.

You can select Sonnet 4.6 now to test your agents before the automatic migration. If your integration specifies a model, use `claude-4.6-sonnet` in future API requests.

See all [deprecation notices](/deprecation-notice/overview).